This invention concerns the use of hydrophobic membranes for drying gel matrices, for example, polyacrylamide or agarose gels commonly used in laboratories for separating DNA and proteins.
Gel electrophoresis in polyacrylamide gels and agarose gels is a common procedure for separation of DNA, RNA and polypeptides. After these materials have been separated within the gel matrix it is common to dry the matrix inorder to either preserve the matrix itself or to detect bands of protein or nucleic acid within the gels. For example, in DNA sequencing procedures, a thin (0.4 millimeter) polyacrylamide gel is placed onto Whatman 3 MM.TM. filter paper and dried until it is less than about 0.05 mm in thickness. The drying procedure entails positioning the gel matrix on the filter paper and placing the filter paper-gel matrix combination within a vacuum-assisted drying apparatus where it is subjected to a vacuum and generally heated to remove liquid from the matrix.
In place of filter paper, gels are also dried on a hydrophilic cellulose dialysis membrane, on a hydrophilic nylon membrane such as a Zeta-probe.TM. Membrane (Cockerill, Analytical Biochemistry, 168:451, 1988), and on chemically interactive membranes which are bonded to the gel during casting, that is, prior to electrophoresis of the components to be separated in the gel. These latter membranes include Gel Bond.RTM. and Gel Bond.RTM. PAG films (manufactured by FMC Corp.) which are polyester films carrying chemical coatings for binding agarose and polyacrylamide gels, respectively.